Electric clock



Jan. 29, 1935.

A. F. POOLE I 1,939,604

ELECTRIC CLOCK Filed Nov. 12, 1950 2 Sheets -Sheet l Jan. 29, 1935. POOLE 1,989,604

ELECTRIC CLOCK Filed Nov; 12,' 1930 INVENT M4 34,

2 Sheets-Sheet 2 v Patented Jan. 29, 1935 UNITED STATES PATENT OFFICE ELECTRIC CLOCK Arthur F. Poole, Ithaca, N. a; Maryline B. Poole administratrlx of said Arthur F. Poole, de-

ceased Application November 12, 1930, Serial No. 495,189

1 Claim. (01. 58-26) An v object of my invention is to provide a new 11 carry synchronized alternating current of and improved method and corresponding appamoderate voltage which may be derived through ratus for governing a clock from a synchronized a transformer from a high tension distribution alternating current. By a synchronized altersystem. By branch conductors from 10 and 11 I 5 nating current I mean an alternating current of current goes through the coil 13 and the stator 5 a power and light distribution system which is winding 34 of the induction motor 3130. This controlled by amaster clockso that its frequency consists of the shaded pole stator 31 and the is held accurately at a definite number of cycles associated rotor 30 constituting a self-starting per second, sixty or twenty-five or whatever the motor. Through the shaft 29, worm 28, wormcase may be. Another object of my invention is wheel 27, shaft 26, worm 25, and worm-wheel 24,

to provide for the operation of such a clock by a constant torque in the direction of the arrow the application of the current to constrain an is put on the drum within the worm-wheel 24.

element to vibrate at a simply related frequency Being loosely mounted on its co-axial shaft this as compared with the frequeney of the applied drum rotates continuously. Within it is the current. For example, the said simply related spiral clock spring 23 with its inner end confrequency may be a sub-multiple of the current nected to the shaft, and its outer end carrying a frequency or the same as the current frequency. shoe 35 having frictional engagement with the Another obiectisto provideacomplete clock that interior of the drum. Thus a constant torque will operate from a local source of power, and in the direction of the arrow is put 11 th h f with an element having a natural periodic motion and through the clock-train 22 a constant torque at approximately a sub-multiple frequency to is transmitted to the escape wheel a which the synchronized current may be applied Returning to the 0011 13 this Surrounds the to hold it in step exactly at the sub-multiple vibrato y 50ft iron feed 12 Which is mechanifrequency. Another object is to provide a clock Ca ly timed to a f q y that is closely approxiwithatuned reed whose natural frequencyisapmate to some convenient sub-multiple of the 25 proximately a sub-multiple of the synchronized alternat current qu y i the 60 1 3- current frequency, and to apply such current Thus. p if the current in coil 13 15 01 to the reed through an electromagnet and therethe frequency of sixty cycles per second, the reed by hold the reed exactly in step at the subay have the ireqlieney of approximate y 12 multiple frequency. All these objects and other cycles per second.- The permanent magnet 14 30 objects of my invention will become apparent on carri h P -P 15 and between which consideration of a limited number of specific lies the reed 12 sup from the block I embodiments thereof which 'I have chosen to have established that when the reed 12 is thus present in this specification by way of example. exposed to the Periodic magn tic fi du to I Will be understood that the following disclothe current in the coil 13, it may be set into 35 sure relates specifically to these particular emvibration and may continue to vibrate at the bodiments of the invention, and that the scope exact sub-multip frequency to which it is D- of the invention will be indicated in the appended p o a tlmed- The Clock-train Pellet claim. and associated parts should all be made very light 40 Referring to the drawings, Figure 1 is a diaso as not to interfere with the vibration of the 40 gram showing apparatus by which my invention reed 12. p may be practiced; Figure 1a shows a modification Whereas I have sugg that with 60 W of the pallet; Figure 1b shows a modification of current the reed may properly be tuned to apthe vibratory reed and associated elements; Fig-v proximately 12 cycles per second, this is largely a ure 2 is a detail cross-section showing the conmatter of mechanical convenience. With 25 cycle 45 nection of the reed and the stud carried by the current it may be practicable to make the reed pallet in Figure 1; Figure 3 shows a modificavibrate at 25 cycles per second. The frequency tion in which the clock train is driven by the of the reed may be related to the frequency of vibrating reed instead of by a local clock-spring the current in the relation of simple small integer as in Figure 1; Figure 3a shows a modified pallet numbers, for example, it may be a multiple, or the 50 and escape wheel for the system of Figure 3; and same, or a sub-multiple. With 60 cycles it may Figure 4 shows a modified disposition of the be inconvenient to have a mechanical element reed and its associated alternating current magtuned at so high a frequency as a multiple or the net. same frequency, and a sub-multiple frequency Referring to Figure 1, the conductors 10 and, suchas12 cycles maybebest. 55

x The reed 12 engages the stud 39 by means of the slot 40, which has the shape shown in Figure 2. Thus an oscillatory movement about the shaft 38 is imparted to the pallet 37 which carries the stud 39, and thus the escape wheel 36 is permitted to turn step by step under the torque to which it is subjected from the spring 23 as described heretofore. The clock train 22 carries the usual time indicating hands on the co-axial shafts 41. Thus these hands move at a rate determined precisely by the frequency of the synchronized current derived from the conductors 10 and 11, and this precise relation is dependent on the fact that the reed 12 can be made to vibrate exactly at a frequency that is a definite sub-multiple of the said current frequency, provided the reed is mechanically tuned to approximately that submultiple frequency.

The design of the gear train 22 is such that in normal operatiorrthe worm 24 turns in the direction of the arrow somewhat faster than its shaft is permitted to turn by the escape mechanism 36-3'7. Thus the spring 23 is kept wound from its outer end to a considerable extent, and the shoe 25 acts as a clutch to prevent unwinding at that end.

To set the clock in operation initially, the current may be turned on and enough alternating magnetic attraction will be applied to the reed 12 to start and build up a vibration therein, so that the clock will be self-starting in this sense. But this clock will be like ordinary pendulum and balance-wheel clocks in that the construction of the clock will detennine whether the torque of its main-spring 23 transmitted to the escape wheel 36 will ordinarily sufiice to start the clock in the absence of current in the coil 13. The clock may or may not be self-starting in this sense.

If the current goes off during normal operation, the clock will continue to run at a rate determined by the actual mechanical tuned frequency of the reed 12, which is made as nearly as practicable the same as the chosen sub-multiple frequency in relation to the current frequency. Then when the current comes on again, the clock goes on at the exact sub-multiple frequency. Most current interruptions on electric distribution lines are of very short duration, so that any departure of the clock from true time due to its interim operation at the natural frequency of the reed 12 will be very small. Of course, if the current stays ofi long enough, the spring 23 will run down and the clock will stop, unless the spring is wound by hand, which can easily be done. When the current goes ofi, of course the torque in the spring will manifest itself at both ends, but the spring cannot unwind at its outer end, because of the irreversible character of the worm and worm-wheel connection between the motor 3130 and the worm-wheel drum 24. Whenever the current comes on after an interruption, the motor 31--30 starts up and winds up the spring to the point of slipping at the shoe 35.

To reduce noise and make the operation smoother, the modification shown in Figure 10; may be employed. Here the pallets 49 and 50 are made as thin leaf springs, thus giving quieter and smoother operation.

Another modification is shown in Figure 112.

Here an alternating current magnet 19 of soft iron is used, energized by the synchronized alternating current in the winding 20. On the same core with winding 20 is another winding 18 which functions as the secondary of a transformer stepping down the voltage to the input side of the rectifier 21, from which the rectified current goes to the coil 13' around the reed 12'. The rectifier 21 may preferably be of the dry plate type, and more specifically, of the kind that passes both half-waves of the alternating current. Thus the reed 12' will be energized by a current that is direct, though somewhat pulsatory, while the magnet 19 will be energized by synchronized alternating current; accordingly the reed 12' will be started and sustained in vibration at a submultiple frequency to the alternating current frequency, provided the reed is tuned naturally to approximately the said sub-multiple frequency. The reed 12' and associated electromagnetic system of Figure 1b take the place of the reed 12 and its associated electromagnetic system of Figure 1; and the system modified thus operates otherwise as described for Figure 1.

In the embodiment of my invention shown in Figure 3, the reed 12" is controlled from the synchronized alternating current conductors 10" and 11" as the reed 12 is controlled from conductors 10 and 11 in Figure 1. But here the clock train 22' is driven from the reed 12' instead of merely limiting its movement as in Figure 1. In Figure 3 the escape wheel 42 has its teeth in the form of round pins 43, and the pallets 37 are beveled so that as they are oscillated by the vibrating reed 12", they push the escape wheel 42 around, and through it drive the gear train 22' and the clock hands. For quietness and smoothness of operation the pallets may be modified by making them as thin flexible leaf springs;

this corresponds to the modification of Figure 1 that is shown in Figure 1a. With the modification of Figure 3 or Figure 3a, the clock train must be made very light and the clock dial must be rather small. Obviously this clock will stop when the current goes off, but will start when the current comes on, and will operate in synchronism as long as the current stays on.

In either Figure 1 or Figure 3, the reed and its associated electromagnetic system may be replaced by the corresponding parts shown in Figure 4. Here the'reed 12" is of tempered steel so that it will have some residual magnetism. The magnet 47 is energized by synchronized alternating current through the winding 48. Thus a vibration of the reed is set up and sustained at a sub-multiple frequency as described for Figure 1 or Figure 3.

' I claim:

In combination, a source of synchronized alternating current of a frequency high enough to be used for light and power; a coil connected thereto. a permanent magnet, a tuned reed associated with the coil and the magnet, the natural frequency of the reed being approximately the quotient of the frequency of the alternating current divided by a small integer number, a clock train whose movement is determined by the vibrations of the reed, and a spring to drive said clock train.

ARTHUR F. POOLE. 

